JPH0730265B2 - Crystal type conversion method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for converting a crystalline form of oxytitanium phthalocyanine, and more specifically, for converting a B-type crystal of oxytitanium phthalocyanine into an A-type crystal. It is about the method.

(Problems to be solved by conventional techniques and inventions) Phthalocyanines are used for coating, printing ink, resin coloring,
It is a compound useful as a catalyst or an electronic material, and has been widely used as a material for electrophotographic photoreceptors.

As a result of detailed examination of the method for producing oxytitanium phthalocyanine, the present inventor has found that there are three types of crystal forms (hereinafter referred to as “A type”, “B type” and “C type” respectively) due to subtle differences in production conditions. ) Is generated. The respective powder X-ray diffraction patterns are shown in FIGS. 1, 2 and 3.

Diffraction angle (2θ) is 9.3 °, 26.3 ° for A type and 7.6 ° for B type, 2
At 8.6 °, C-type has characteristic diffraction peaks at 7.0 °, 15.6 °, 23.4 ° and 25.5 °.

The three types of crystals are usually obtained as a mixture in many cases, but since the physical properties are different from each other, if they are used as a mixture, various troubles due to the stability of the physical properties are likely to occur.
Therefore, it goes without saying that it is desirable to obtain pure crystalline form of oxytitanium phthalocyanine in the production thereof. More preferably, it is preferable to obtain and use a stable crystal. This is because oxytitanium phthalocyanine is rarely used alone, and is usually subjected to addition of various auxiliaries and dispersion treatment at the time of use, but it is inevitable that the crystal form changes at these stages. In addition, since the physical properties thereof change, it is easy to cause troubles such as poor affinity with the auxiliary agent and deterioration of dispersion stable type.

For example, oxytitanium phthalocyanine is often commercialized by dispersing it in various polymers, solvents, etc. as a usage form, then coating and drying it. At the same time, since the interaction with the polymer or solvent is different due to the difference in the crystal type, if a mixture of different crystal types or an unstable crystal is used, the dispersibility is hindered, Physical properties often become unstable. In order to eliminate such defects, it is necessary to produce pure and stable single crystal oxytitanium phthalocyanine, and development of a production method thereof is strongly desired.

(Means for Solving the Problems) As a result of detailed study on the stability of the above-mentioned three types of oxytitanium phthalocyanine crystals, the present inventor found that the B-type crystal is the most unstable and easily changes to another crystal type. It has been found. Further, the A type and the C type showed almost the same stability.

The present inventor has conducted diligent studies to convert a B-type crystal of oxytitanium phthalocyanine into a more stable A-type crystal, and as a result, converts the B-type crystal into an A-type crystal by treating the B-type crystal under certain conditions. The inventors have found that it is possible to achieve the present invention. That is, the gist of the present invention resides in a method for converting a B-type crystal of oxytitanium phthalocyanine into an A-type crystal, which comprises heating the B-type crystal of oxytitanium phthalocyanine in an organic solvent in the presence of the A-type crystal. .

Hereinafter, the present invention will be described in detail.

The organic solvent used in the present invention is not particularly limited, but one having a boiling point of 130 ° C. or higher is suitable. For example, naphthalene such as α-chloronaphthalene, β-chloronaphthalene, α-bromonaphthalene, α-methylnaphthalene, α-methoxynaphthalene, diphenyl ether, 4,4′-dichlorodiphenyl ether, 3,3′- Diphenyl ethers such as dimethyl diphenyl ether, diphenyl methane,
Diphenylmethanes such as 4,4′-dimethyldiphenylmethane and 3,3′-dichlorodiphenylmethane, halobenzenes such as 1,4-dichlorobenzene, 1,2,4-trichlorobenzene and bromobenzene, nitrobenzene, 1 Nitrobenzenes such as 3,3-dinitrobenzene and 1,2,4-trinitrobenzene, N-methylpyrrolidone, 1,3-dimethyl-
2-imidazolidinone, dimethyl sulfoxide, N, N-
Examples thereof include dimethylformamide, quinoline, sulfolane and the like. Of course, an organic solvent having a boiling point of 130 ° C. or lower can be used, but when a treatment temperature of 130 ° C. or higher is used, pressurization is required and the operation becomes slightly complicated.

The amount of the organic solvent used can be arbitrarily selected, but is preferably selected from the range of 4 to 30 times the oxytitanium phthalocyanine. If the amount of organic solvent used is less than this range, the viscosity of the treatment liquid will be high, making uniform mixing difficult, and if it is more than this range, the amount treated per unit volume will be small, so it is desirable to avoid it. .

The heat treatment temperature is preferably in the range of 130 to 300 ° C. If the value is lower than this range, the conversion speed becomes low and the processing time becomes long. Further, it is preferable to avoid it because the solvent and oxytitanium phthalocyanine used in the treatment at 300 ° C. or higher may be thermally decomposed.

The amount of the oxytitanium phthalocyanine type A crystal to be coexistent can be arbitrarily selected, but it is preferably in the range of 5 to 60% relative to the type B crystal. Since the conversion rate from B-type crystals to A-type crystals is proportional to the amount of A-type crystals that coexist,
If it is less than%, the processing time becomes long and it is not practical. Also, A
No conversion occurs at all without the coexisting type crystals.

(Example) Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1 A 300 ml flask equipped with a thermometer and a stirrer was charged with 6 g each of B-type crystals and A-type crystals of oxytitanium phthalocyanine, 200 ml of α-chloronaphthalene was added and the temperature was raised to 200 ° C. The suspension was stirred for 3 hours. This suspension 120
After cooling to ℃, it was passed to obtain a wet cake of oxytitanium phthalocyanine. Then α attached to the wet cake
-Chloronaphthalene was removed by washing with methanol and then dried under reduced pressure at 60 ° C to obtain 11.5 g of oxytitanium phthalocyanine. The powder X-ray diffraction pattern of the obtained oxytitanium phthalocyanine was in agreement with Fig. 1 and it was a pure A-type crystal.

Examples 2 to 15 and Comparative Examples 1 to 5 Table 1 shows the results of the same experiments as in Examples except that the type of solvent, the treatment temperature, the amount of A-type crystals added, and the like were changed.

[Brief description of drawings]

FIG. 1 is a powder X-ray diffraction pattern of the A-type crystal of oxytitanium phthalocyanine, which has strong diffraction peaks at diffraction angles (2θ) of 9.3 ° and 26.3 °. FIG. 2 is a powder X-ray diffraction pattern of the B-type crystal of oxytitanium phthalocyanine, which has strong diffraction peaks characteristic at diffraction angles (2θ) of 7.6 ° and 28.6 °. Figure 3 is a powder X-ray diffraction pattern of the C-type crystal of oxytitanium phthalocyanine. The diffraction angles (2θ) 7.0 °, 15.6
It has strong diffraction peaks characteristic at °, 23.4 ° and 25.5 °.

Claims (1)

[Claims] 1. A method for converting a B-type crystal of oxytitanium phthalocyanine into an A-type crystal, which comprises heating the B-type crystal of oxytitanium phthalocyanine in an organic solvent in the presence of the A-type crystal.